Available in Japanese Market. Please visit Telescope Center Eye-Bell.
I put some on ebay, too.

SkyWatcher(TM) AZ GTi/GTe does not have an autoguide port because it is not equatorial mount. Therefore, autoguide must be done through external device like PC.

“AZ-AUTOGUIDEPORT” gives a ST4 autoguide port to yout AZ-GTi/GTe.
Pin assign is following

With stand-alone type autoguider, such as MGEN or NEX-Guide, you can do two-axis autoguide without PC.

Configuration

Configuration is simple. Set autoguide speed and hemisphere, by rotary switch.

Autoguide Speed	x0.125	x0.25	x0.5	x0.75	x1.0
North Hemisphere	1	2	3	4	5
South Hemisphere	F	E	D	C	B

DEC Backlash Compression

RA motor keep moving in the same direction, and less have backlash.
But DEC motor may move both direction. When moving direction changes, there are certain delay time until it start moving by backlash.

According to my experiment, AZ GTi’s backlash is too large- is about 60 arc-seconds.

DEC Backlash Compression mechanism will move quickly backlash area in about 0.2 second, then slow down to normal autoguide speed. This eliminates most part of backlash-delay time.
You can configure backlash compression level from 42.5 to 77.5 arc-second.